1. Field of the Invention
The present invention relates to a communication device which can be freely inserted into and extracted from a terminal device, and an authentication method between a communication device and a terminal device and a method of wireless-connecting terminals using a communication device.
2. Description of the Related Art
Various communication devices which can be freely inserted into and extracted from a terminal device have been conventionally proposed. For example, Japanese Patent Laying-Open (Kokai) No. Heisei 8-149035 (hereinafter referred to as Literature 1) proposes a card-type radio communication device which has a means for providing the interface with an information terminal, an antenna and a radio transmission and reception circuit and which is inserted for use into a PCMCIA (Personal Computer Memory Card International Association) standard slot of an information terminal. Literature 1 also discloses a technique of preventing false use of a card-type radio communication device by others by providing the card-type radio communication device with a portion to which an authentication module assigned to an individual user of a GSM (Global System for Mobile Communication) system is attached, inputting a password number by a user when the card-type radio communication device mounted with the authentication module is inserted into an information terminal and collating the input password number and a password number set at the authentication module in advance.
Among other communication devices which can be freely inserted into and extracted from a PCMCIA standard slot are a data communication radio transceiver recited in Japanese Patent Laying-Open (Kokai) No. Heisei 8-321791 (hereinafter referred to as Literature 2) and a radio terminal recited in Japanese Patent Laying-Open (Kokai) No. Heisei 11-154886 (hereinafter referred to as Literature 3).
Although as a communication device which can be freely inserted into and extracted from a terminal device, various devices have been conventionally proposed as recited in Literatures 1 to 3, they have the following shortcomings.
(1) Common mobile communication services include various systems such as a GSM system, a CDMA (Code Division Multiple Access) system, a PDC (Personal Digital Cellular) system and a PHS (Personal Handyphone System) system. Therefore, in order to cope with a wide variety of radio infrastructures, it is necessary to prepare a communication device adapted to each mobile communication service and replace the communication device by other device for use. The problem in this case is that a user is not allowed to immediately know to which mobile communication service the currently used communication device is adapted. The reason is that since the devices recited in the above Literatures 1 to 3 are premised on a specific mobile communication service as a mobile communication service, they are not designed to make a user know a kind of communication device.
(2) Although the card-type radio communication device recited in Literature 1 uses a password number for preventing false use by others, for that reason the user needs to input a password number every time the card-type radio communication device is attached to a different terminal device, which hinders facility of the device.
(3) Conventional communication devices of this kind are premised on that they are used for mobile communication services. Therefore, when a user inserts a communication device into each of such terminals as a PDA (Personal Digital Assistant), a portable phone and a personal computer (PC) each user owns to communicate between communication devices, thereby wireless-connecting a plurality of terminals, a mobile communication service should be used for every communication to incur charges and make high-speed communication difficult. Although there is a radio LAN system as a technique of locally connecting terminal devices, because the system is large in scale and requires special knowledge for setting a communication address, its home use can not be realized with ease.